Regensburg 2002 – wissenschaftliches Programm
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SYOH: Organische Halbleiter
SYOH 7: Poster
SYOH 7.41: Poster
Montag, 11. März 2002, 18:00–21:00, C
Influence of electrode morphology on charge carrier injection and transport in organic devices — •Jörg Stephan1, Sergey Novikov2, Alexandra Buchsteiner1, and Ludwig Brehmer1 — 1Institute of Physics, University of Potsdam, 14415 Potsdam, Germany — 2A.N. Frumkin Institute of Electrochemisry, 117071 Moscow, Russia
Current interest in studies of the morphology of electrode surfaces and metal/organic interface is due to its significant effect on organic device performance and stability. In particular charge carrier injection rates depend strongly on the roughness of the electrode. A recently derived closed analytical expression[1] connecting roughness profiles of smooth interfaces with the distribution of the electrostatic potential in the transport layer is used to calculate the distribution of the electric field at the electrode surface and, thus various injection properties of the contact (field dependence of total injection current for Fowler-Nordheim and Schottky-Richardson injection, surface distribution of injection rate etc.). Surface topologies for different ITO and Au surfaces as determined from our AFM measurements are used as input parameters for the determination of the field distribution and injection properties at the surface. We compare theoretical predictions of the surface charge distribution with simultaneous measurements using Kelvin probe microscopy (KPM). Since rough surfaces are also expected to influence bulk carrier transport in the organic layer we perform similar AFM and Kelvin probe measurements for thin organic films of varying thickness and discuss implications on the optimal design of electrodes for OLEDs and Photovoltaic cells.
[1] S.V. Novikov, Proc. SPIE,bf 84, 4104(2000)